Open tubular liquid chromatography with thermal lens detection

Abstract

This work was supported by a grand-in-aid from the Toyota Foundation (No.82-1-III-031) and the Ministry of Education of Japan (No.

Column efficiency in micellar electrokinetic capillary chromatography

“…Extracolumn processes (principally injection and detection) can also cause band dispersion. In this work, on-column electroinjection (10) and on-column laser-excited fluorescence detection (13) were performed. Hence, extracolumn band dispersion is expected to be neg-…”

Dual-beam absorbance measurements by position-sensitive detection

“…Substituting into eq 9 and 10 from eq 5-8 and simplifying 7o r(L -2m) = 70 S(2X + 2m -L) (13) Beyond working at an electronic null, one wishes to work at an optical null in order to improve the signal-to-noise ratio (S/N). An optical null occurs when the incident reference and sample beams are of equal intensity prior to any absorbance, i.e., 7oR = 70 S. From eq 13 the optical null condition states that L = X + 2m (14) which further suggests that 70iR and 70 S are equidistant from the center of the PSD, from the symmetry of eq 14 and Figure 2. If an absorbance occurs in 70|S, the resultant current at the PSD is 7S, and the ratio signal becomes «¡of 7"(^) + , ^2) -7 Jf)from eq 5-11. After simplification with eq 14, eq 15 becomes Since 70iR…”

“…(13) Welz, B.; Melcher, M. Analyst (London) 1984, 109, 573-575. (14) Welz, B.; Melcher, M. Analyst (London) 1984, 109, 577-579. (15) Welz, B.; Schubert-Jacobs, M. J.…”

“…The common modes of absorbance detection employ fixed-wavelength, variable-wavelength (scanning), or multichannel (photodiode array) detectors (7). If improved solute detectability is a concern, many laser-based approaches to HPLC and FIA absorbance detection have been developed based upon thermal lens spectroscopy (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), Fabry-Perot interferometry (19), indirect polarimetry (20), and high-frequency amplitude modulation (21,22). In each of these laser-based methods, quantitative analysis is ultimately limited by some form of noisé.…”

Detection of nonfluorescent molecules using differential interference contrast thermal lens microscope for extended nanochannel chromatography

“…Because TLS has high sensitivity for nonfluorescent molecules in microspace 7–9, we could apply the TLM to many microchip applications including electrophoresis 10, immunoassay 11 and metal ion analysis 12. In addition, TLS has often been employed for microchip and capillary chromatography 13–16. However, the conventional TLS could not be employed for a measurement in nanochannel due to its smallness.…”